Synthesis And Property Investigation Of Functionlized Magnetic Nanoparticles

1. The magnetite (Fe3O4) nanoparticles (MNPs) coated with PEG diacid via covalent bonds were prepared for magnetic resonance imaging (MRI). The surface of MNPs was first coated with (3-aminopropyl) triethoxysilane (APTES) by a silanization reaction and then linked with PEG diacid via the reaction between -NH2 and -COOH to form well-dispersed surface functionalized biocompatible MNPs. The obtained nanoparticles were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and thermogravimetry (TG). The MNPs had an average size of 20nm and exhibited superparamagnetism and high saturation magnetization at room temperature. In addition, PEG-6000 diacid coated Fe3O4 nanoparticles were used to perform the MRI experiments on the living rabbits with VX2 malignant tumor, the results showed that these nanoparticles appear to be a promising vehicle for MR imaging.2. Biocompatible magnetic fluid based on dextran-coated Fe3O4 magnetic nanoparticles (MNPs) was prepared through a one-step method. XRD, TEM, DLS, VSM, MRI and histology evaluation of MF suggested that the MF laid a good foundation for further research of hyperthermia treatment. To determine the exothermic effect of magnetic fluid in an alternating magnetic field in vitro, magnetic fluid with different concentrations was prepared and placed in an alternating magnetic field for 20 minutes. The influences of the dose of magnetic fluid and current of magnetic field oil on the heating ability were studied. The results show that the magnetic particles with 10-20 nm diameter can produce an obvious heating effect and generate enough energy to heat tumor tissue and perform effective hyperthermia.3. Magnetic poly(methyl methacrylate) (PMMA) microspheres were prepared by double-miniemulsion polymerization. First, oleic acid coated magnetite particles synthesized by means of coprecipitation were dispersed into octane to obtain a ferrofluid. The ferrofluid and MMA were emulsified to form O/W emulsion, respectively. Subsequently two miniemulsions were mixed together for polymerization. The obtained magnetic polymer particles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and thermogravimetry. The results showed that oleic acid coated magnetite particles were well encapsulated in PMMA.4. Superparamagnetic magnetite/polystyrene (PS) composite particles were prepared by inverse emulsion polymerization with water-based ferrofluid as dispersing phase and organic solvent and styrene (St) as continuous phase. The resultant brownish Fe3O4/PS emulsion showed magnetic behavior in an applied magnetic field. The obtained magnetic Fe3O4/PS microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and thermogravimetry (TG). The magnetic Fe3O4/PS microspheres with a diameter of 200 nm were observed. The results showed that magnetite particles were well encapsulated in PS and the composite particles have high magnetite contents, which were more than 15%.